The Do Sono River (Portuguese: Rio do Sono) is a river of Tocantins state in central Brazil. It is a right tributary of the Tocantins River.

The river has its headwater in the 158,885 hectares (392,610 acres) Jalapão State Park, a fully protected conservation unit created in 2001. The Do Sono forms at the confluence of the Novo and Soninho on the northwest boundary of the state park.

• List of rivers of Tocantins